字符串解析出所有ip地址

/*given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given "25525511135",return ["255.255.11.135", "255.255.111.35"]. (Order does not matter)*/#include <vector>#include <string>#include <iostream>#include <algorithm>class Solution{public:std::vector<std::string> restoreIpAddresses(std::string s){std::string::iterator l1,l2,l3;std::string str1,str2,str3,str4;std::vector<std::string> vec;for(int i=1;i<=3;++i){l1=s.begin()+i;str1=std::string(s.begin(),l1);if(!isValid(str1))continue;for(int j=1;j<=3;++j){l2=l1+j;str2=std::string(l1,l2);if(!isValid(str2))continue;for(int t=1;t<=3;++t){l3=l2+t;if(l3>=s.end())break;str3=std::string(l2,l3);str4=std::string(l3,s.end());if(!isValid(str3) || !isValid(str4))continue;vec.push_back(str1+"."+str2+"."+str3+"."+str4);}}}return vec;}private:bool isValid(const std::string& sub){if(sub.size()==1)return true;else if(sub.size()==2 && sub[0]!='0')return true;else if(sub.size()==3 && sub[0]>='1' && sub[0]<='2'){if(sub[0]=='2' &&((sub[1]=='5' && sub[2]>'5')||(sub[1]>'5')))return false;return true;}return false;}};int main(int argc,char* argv[]){std::string str("172162541");Solution s;std::vector<std::string> vec=s.restoreIpAddresses(str);std::for_each(vec.begin(),vec.end(),[](const std::string& s){std::cout<<s<<std::endl;});return 0;}